Naturally Occurring 12Dioxane Derivatives

Unbelievably, the 1,2-dioxane scaffold is sometimes found in nature [1,2]. Chemists have imagined that the 1,2-dioxane derivatives would be unstable in air since the oxygen-oxygen bond dissociation energy is estimated to be only 34 kcal/mol [3]. However, artemisinin isolated from Artemishia annua [411] and yingzhaosu isolated from Artabotrys unciatus [12-16] are the most famous 1,2-dioxane analogs and have very strong antimalarial activity like quinine, chloroquine, and mefloquine [17] (Fig. 1). The 1,2-dioxane derivatives, found in Eucalyptus grandis and related species in Australia, inhibit root formation in cuttings [18-20] and also possess an auxin-like activity (promontory) as well as an abscissic acid-type activity (inhibitory) [21,22] (Fig. 2). Marine sponges contain the antitumor cyclic peroxy ketals and a series of related ketals, such as chondrillin and plakorin, isolated from Pla-kortis lita [23-33]. Plakortis sp also produces diverse 1,2-dioxolanes, such as plakinic acids [34-36] (Fig. 2). Many further 1,2-dioxane derivatives may be found in the natural environment in the near future.